BQ25703A: About BATDRV pin

Tsukui Yusuke

Guru 21930 points

Part Number: BQ25703A

Hi Team,

Could you tell me about the /BATDRV pin?
Data sheet describes the following.
”It goes 10 V below VSYS to fully turn on BATFET.”

Please tell me the reason why it is listed as 10V.
I think that it depends on the characteristics of use Pch FET.

Best Regards,
Yusuke

over 6 years ago

0 Joel Hernandez II over 6 years ago

TI__Mastermind 25800 points

Hey Tsukui,

This does not depend on the characteristics of the PFET.

The charger will pull the gate of the PFET 10V below the source, no matter the PFET. At that point it is the responsibility of the designer to select an appropriate FET to meet these conditions; however the 10V rating should cover most power PFETs in the power range this charger supports.

Regards,

Joel H

0 Tsukui Yusuke over 5 years ago in reply to Joel Hernandez II

Guru 21930 points

Joel-san,

Thank you for your response and support.
Could you be more specific?

For example,
When Vsys is 1.024V and Vbat = 4.2V , Vbus=5 to 12V,
It is difficult to generate a potential difference of 10V.
Can you tell me about / BATDRV operation for 1cell?

Regards,
Yusuke

0 Joel Hernandez II over 5 years ago in reply to Tsukui Yusuke

TI__Mastermind 25800 points

Hey Tsukui,

Now I understand. Yes, below a certain voltage, the charger will not generate a negative voltage. In that scneario, the charger can only pull the /BATDRV pin to GND.

Regeards,

Joel H

Power management

Power management forum

BQ25703A: About BATDRV pin